1. Field of the Invention
The present invention relates to a polishing material comprising a fluid containing grinding particles, a grinding material (particularly grinding particle body for abrasion-grinding in which reversible phase transition between liquid and solid states is possible at normal temperatures (0-65xc2x0 C.)), polishing method, and a polishing apparatus with which to move a polishing material relative to a work thereby giving a polish to the work.
2. Prior Art
With the rapid development of technological innovation, demand for high quality industrial products becomes acute; and processed objects (to be referred to as xe2x80x9cworkxe2x80x9d hereinafter) such as industrial products or parts requiring abrasion-polishing or abrasion-grinding come to have a complicated shape which often requires finest and minutest precision for processing. However, the last finishing process of such a work where the finest surface polishing or the maximum precision of groundwork is required is generally achieved even today by human hands. Therefore, if this manually achieved process could be substituted for by a machine-operated process or a process enabling the reduction of labor cost, it would be beneficial because it would reduce cost involved in processing, or time required for the process. Further, the manually-operated process has a precision limit in the finest surface polishing no matter how skilled the hands may be.
To meet such a situation, studies on a method for enabling the high-precision surface polishing of a work using a soft lapping stone have been continued. This is a polishing method using a polishing stone comprising of a soft polymer material such as polyvinyl acetal, sodium alginate or the like, as a bonding agent. The polishing based on soft lapping like this has been mainly used for the fine surface polishing of a silicone wafer required for fabrication of an integrated circuit.
The inventors of this Application proposed a polishing method which consists of using a magnetic fluid containing grinding particles whose orientation can be controlled by a magnetic field, immersing a work in the magnetic fluid, and vibrating or rocking the magnetic fluid with respect to the work while a magnetic field with a specified intensity being applied to the fluid. The polishing method based on the use of a magnetic fluid includes, for example, those disclosed by Japanese Patent Laid-Open Nos. 1-135466, 4-336954 and 4-41173.
However, with such a polishing method, the strains given by grinding particles on the surface of work are so small that their polishing effect is weak, because the polishing material is a highly fluidic liquid. Because of this, this method is not suitable for a process requiring abrasion-grinding, or a process requiring coarse polishing introduced before fine polishing, although it may be utilized for the uniform surface polishing of the entire surface of a work during the final process.
This conventional technique uses a magnetic fluid, puts it under a magnetic field having a specified intensity, and polishes a work while controlling the orientation of grinding stone particles, but poses a problem when used for polishing a work requiring high-precision polishing in a direction in a tri-dimensional space.
To meet this inconvenience, the present inventors paid attention to the fact that a fluidic abrasive containing grinding store can vary its form freely in accordance with the shape of the surface to be ground, and can polish even the surface of a cleft or a narrow, recessed surface rejecting the access of human hands or a tool. However, because the fluidic abrasive exerts a less pressure against the surface of a work than a solid abrasive that is otherwise the same in configuration, it is not suitable for rapid grinding or coarse polishing. Therefore, they proposed a polishing material which combines the merits of both fluidic and solid abrasives, that is, a material capable both of polishing a surface having a complicated shape, and of achieving highly effective polishing. Use of this proposed polishing material consists of injecting fluidic abrasive stone containing grinding particles into a work, solidifying it at a low temperature, and moving the thus obtained solid abrasive relative to the surface of work, thereby achieving polishing or grinding of the latter. The conventional abrasive stone includes metal bond abrasives, resin bond abrasives, electrical bond abrasives, gelatin texture abrasives, etc. However, because they have been prepared to take a certain shape before they are used, it is difficult to freely vary their shape in accordance with the surface to which they are applied.
Actually, the method for polishing or grinding a work on the basis of a mechanical force imposed by a solid J abrasive with a specific shape is limited to abrasion grinding or coarse polishing because it does not allow high precision polishing. Further, polishing with an apparatus incorporating a solid abrasive has been conventionally used for polishing of a two-dimensional surface and hardly used for polishing of a surface having a tridimensional expanse because of the structural rigidity inherent to such a solid abrasive.
Further, polishing by the method of immersing a fluid containing grinding particles to the surface of a work to be polished, and moving the fluid with respect to the surface thereby to give a polish on the surface has a very weak effect, because the polishing material is a highly fluidic liquid, and the contact pressure exerted by the grinding particles against the surface to be polished is small. Because of this, this method is not suitable for a process requiring abrasion-grinding, or a process requiring coarse polishing introduced before fine polishing, although it may be utilized for the uniform surface polishing of the entire surface of a work during the final process. This conventional method consisting of using a magnetic fluid, putting it under a magnetic field having a specified intensity, and polishing a work while controlling the orientation of grinding stone particles poses a problem when a work requiring high-precision polishing must be polished in a direction in a tri-dimensional space.
Furthermore, the polishing material solidifies when exposed to low temperatures close to xe2x88x9215xc2x0 C. while the atmospheric temperature prevalent during polishing is close to xe2x88x9230xc2x0 C. This temperature difference requires some adjustment when the method is to be put into practice.
An object of the present invention is to provide a grinding particle body in which the phase transition from a liquid abrasive to a solid abrasive occurs in a temperature range facilitating practicality, and which enables polishing or grinding at normal temperatures.
Another object of this invention is to orientate grinding particles in a specific direction by utilizing the orientation characteristic of a grinding particle orientation material, and externally applying an electric or magnetic field to the grinding particles, thereby improving the grinding and polishing properties of the particles.
The present invention provides a polishing material which not only retains the merits of a fluid grinding stone containing grinding particles, that is, the property of freely changing its shape in accordance with the shape of the surface to be polished, and the property of invading into a narrow closed recessed surface inaccessible to human hands or a tool, but is also provided with the merit of a solid grinding stone, that is, the property of enabling rapid abrasion-grinding or coarse polishing, and a method using such a material. To achieve this object, this method is configured such that a fluid containing grinding particles is solidified or gelatinized in accordance with the shape of a work, and the resulting solid or gel material is moved relative to the work, thereby polishing or grinding the work.
Further, the invention provides a polishing material wherein the fluid containing grinding particles is a magnetic fluid capable of controlling the orientation of grinding particles in the presence of a magnetic field, and is solidified or gelatinized while being in the presence of a magnetic field.
The invention provides a polishing material wherein the fluid containing grinding particles is an electric rheology fluid capable of controlling the orientation of grinding particles in the presence of an electric field and is solidified or gelatinized in the presence of an electric field. The invention provides a polishing material wherein the grinding particles polarize in the presence of an electric field.
The invention provides a polishing material wherein the fluid, containing water as a substrate, solidifies by being exposed to a temperature not higher than its solidification point, and liquefies by being exposed to a temperature higher than the solidification point.
The invention provides a polishing material wherein the fluid, containing as a substrate a substance capable of polymerizing in the presence of light, solidifies or gelatinizes by being exposed to light.
The invention provides a polishing material wherein the substance capable of polymerizing is at least one arbitrarily chosen from the group comprising styrene, methyl methacrylate and vinyl acetate.
The invention provides a method for preparing a polishing material comprising the steps of pouring a fluid containing grinding particles on the surface of a work to be processed; and solidifying or gelatinizing the fluid in accordance with the shape of the surface of work to be processed.
The invention provides a method for polishing or grinding a work comprising the steps of solidifying or gelatinizing a fluid containing grinding particles in accordance with the shape of a work; and moving the resulting solid or gel material relative to the work.
The invention provides a method for polishing or grinding wherein the relative movement occurs as a mechanical vibration between the material and the work.
The invention provides a method for polishing or grinding a work comprising the steps of solidifying or gelatinizing a magnetic fluid capable of controlling the orientation of grinding particles in the presence of a magnetic field, in accordance with the shape of a work; solidifying or gelatinizing the fluid while it is exposed to a magnetic field; and moving the resulting solid or gel matter relative to the work.
The invention provides a method for polishing or grinding wherein the relative movement is evoked by alternate magnetic fields.
The invention provides a method for polishing or grinding a work comprising the steps of solidifying or gelatinizing a fluid containing dielectric grinding particles capable of polarizing in the presence of an electric field in accordance with the shape of a work; solidifying or gelatinizing the fluid while it is exposed to an electric field; and moving the resulting solid or gel material relative to the work.
The invention provides a method for polishing or grinding wherein the relative movement is evoked by alternate electric fields.
The invention provides a polishing method comprising the steps of solidifying the fluid; liquefying again part of the solid material on the surface in contact with a work to be processed; and moving the solid material relative to the work.
The grinding particle body for abrasion-grinding according to the invention is characterized by containing as the main ingredient of solvent at least one of the compounds represented by the following general formula,
R1xe2x80x94COOxe2x80x94R2
where R1=CaH2a+1, 10xe2x89xa6axe2x89xa625, and R2=CbH2b+1, 1xe2x89xa6bxe2x89xa625, and by dispersing grinding particles or a grinding particle orientation material in that compound.
A grinding particle body for abrasion-grinding is characterized by containing as the main ingredient of solvent at least one out of stearic acid esters or myristic acid esters.
A grinding particle body for abrasion-grinding is characterized by containing grinding particles which are made of at least one out of aluminum oxide or diamond whose particle-diameter distribution has the central point at 2 to 9 xcexcm.
A grinding particle body for abrasion-grinding is characterized by having the grind particle orientation material which contains as its main ingredient ferrite particles whose particle distribution has the central point at 2 xcexcm or less.
A grinding particle body for abrasion-grinding wherein reversible phase transition occurs between liquid and solid states with the melting point of the solvent serving as the phase boundary.
A grinding particle body for abrasion-grinding is characterized by being used as a polishing material when it turns into a solid as a result of phase transition.
A grinding particle body according to this invention is effectively used as a polishing material, and use thereof consists of pouring a liquid grinding particle body for abrasion-grinding on to the surface to be polished for contact; converting the body to a solid at a temperature range of 0-65xc2x0 C.; and moving the resulting solid relative to the surface to be polished. In addition to the method whereby a liquid grinding particle body for abrasion-grinding is poured, and solidified in the presence of a magnetic field for use, there is a method whereby a liquid grinding particle body is molded to have a specific form, and is stored as such. This method comprises the steps of preparing a mold for injection; injecting a liquid grinding particle body for abrasion-grinding into the mold; converting it to a solid in the presence of a magnetic field, thereby producing a solid grinding stone; repeating the last process to obtain many stones for storage; and using them for abrasion as needed. This method makes it possible not only to rapidly meet the urgent need for abrasion, but to prepare grinding stones having a specific shape in accordance with the shape of a frequently used work.
A polishing apparatus according to this invention provides not only merits inherent to a solid grinding stone but also merits inherent to a liquid grinding body: it develops a comparatively strong power for polishing or grinding, while it freely varies its shape in accordance with the shape of a surface to be processed, and thus invades into a narrow, closely recessed surface rejecting the access of human hands or a solid grinding stone.
Use thereof consists of using a polishing material which has solidified or gelatinized in accordance with the shape of the surface of a work to be processed; and moving the polishing material relative to the work, thereby giving a polish to the work. The relative movement occurs as a mechanical vibration of the polishing material against the work. However, if the polishing material is a magnetic fluid capable of controlling the orientation of grinding particles in the presence of a magnetic fluid, it is possible to evoke the relative movement by applying alternate magnetic fields to the polishing material. Alternatively, if the polishing material is a fluid containing grinding particles capable of polarizing in the presence of an electric fluid, and has solidified or gelatinized in the presence of an electric field, it is possible to evoke the relative movement by applying alternate electric fields to the polishing material.
The relative movement may occur in a uni-, two- or tri-dimensional direction, depending on the three dimensional expanse of the surface of a work to be polished. The relative movement proceeds from one dimension to another in a sequential order, or along the dimensions at the same time.
The polishing apparatus according to this invention comprises a driving means for evoking a relative movement between a polishing material formed in accordance with the shape of the surface of a work to be processed, and the work; a pressure detection means for detecting pressure generated on the work by the polishing material during the relative movement; and a control means for controlling the stroke distance of relative movement according to the value of pressure detected by the pressure detection means, a specific value of pressure having been fed to the control means, and the control means controlling the driving means such that the value of pressure during the relative movement corresponds with the specified value.